Since the photoelectric display technology has become more mature, the application fields of display devices become more widely. With the advantages of long lifetime, high optical efficiency, low radiation and low power consumption, Liquid Crystal Displays (LCDs) have recently become the mainstream development trend of display device products, gradually replacing conventional ray tube display devices.
The exposure machine as a regular equipment used in the fabrication process of the LCDs is principally configured for exposing the substrate, with an aim of transferring mask pattern information of the mask plate onto the substrate. After the exposure, subsequent processes such as developing and etching are used to form patterns of individual structural units required by the array substrate and the color film substrate in the LCD. The working procedure of the exposure machine is as follows: an arc beam (or beams in other forms) with an initial acceleration velocity of zero is emitted by the exposure machine; the beam is then accelerated though an acceleration region and used to scan the substrate with a uniform velocity, wherein the substrate is coated with a photosensitive substance thereon; and then the velocity of the beam is reduced to zero through a deceleration region and the exposure is finished. Herein the motion characteristics of the beam will have an influence on the exposure effect. For example, the motion characteristics of the beam comprise the scan velocity of the beam, the initial position and the ending position of the uniform scan and so on.
However, the inventors found that the conventional technology has at least the following disadvantages during research and development. That is, an exposure defect will occurs when the parameters of the exposure machine are not properly set. For example, instead of scanning and passing through the substrate with a uniform velocity, the beam emitted by the exposure machine scans and passes through the substrate in the acceleration or deceleration mode, which will cause the exposure amount received by the substrate different from the desired exposure amount. However, the reason for generating exposure defects can not be determined by using the existed detecting technology.